1. Field of the Invention
The present invention relates to a method for measuring a fiber content in a mixed-spun fiber, particularly a method for measuring fiber content of polyethyleneterephthalate (PET) and polytrimethyleneterephthalate (PTT) fibers in a mixed-spun fiber. More particularly, the present invention relates to a method for measuring the fiber content of PET and PTT fibers in a mixed-spun fiber material in which various types of fibers are mixed by using a polarized light microscope.
2. Description of the Related Art
FIG. 1 is a view illustrating the structure of a conventional fiber product in which polyethyleneterephthalate (PET) fiber, polytrimethyleneterephthalate (PTT) fiber, and other fiber components are mixed-spun.
As illustrated, a product is manufactured by mixing the PET and PTT fibers without using the PET fiber alone because this makes it possible to improve elastic force without using spandex fiber. This is beneficial because the PTT fiber has excellent elastic recovery durability whereas the elastic recovery force of the spandex fiber is reduced by repeated elongation thereof several times.
The PET fiber and PTT fiber may be represented by the following Formula 1.

When the content of the PTT fiber is increased in a fiber product, touch and elasticity are improved. However, the PTT fiber is expensive, and thus a desired physical property may be implemented while reducing the cost by mixing relatively inexpensive PET fiber therewith.
TABLE 1ClassificationPTTPETTouchSoft touchStiff touch comparedto PTTElasticityExcellentInsufficientDyeabilityExcellentExcellentDyeing temperature110° C.130° C.Glass transition temperature (Tg)45 to 65° C.69 to 115° C.Melting temperature (Tm)228° C.265° C.Heat treatment temperature140° C.180° C.PriceHighReasonable
Table 1 is a table that compares general physical properties of PTT and PET fibers, and required physical properties are satisfied by controlling the content of each component so as to provide suitable characteristics and physical properties required for various kinds of fiber products.
In the related art, when the PTT fiber is mixed-spun with other fibers which are different in solubility and form, the content thereof may be measured. However, when the PTT fiber is mixed-spun with PET fiber, which is the same the PTT fiber in solubility and form, there is a problem in that there is no method of measuring the fiber content thereof.